Slashdot videos: Now with more Slashdot!

View

Discuss

Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).

Researchers have created a new nanoparticle that could someday act as a virtually all-purpose diagnostic tool to detect many inflammatory diseases in their earliest stages, including heart disease, Alzheimer's, and arthritis. The specially-designed nanoparticles seek out hydrogen peroxide (thought to be overproduced in trace amounts in the early stages of most diseases that involve some sort of chronic inflammation in the body), and emit light when they encounter it.

The specially-designed nanoparticles seek out hydrogen peroxide (thought to be overproduced in trace amounts in the early stages of most diseases that involve some sort of chronic inflammation in the body), and emit light when they encounter it.

No good. I just can't see how this going to work at all for Paris Hilton.

"The specially-designed nanoparticles seek out hydrogen peroxide (thought to be overproduced in trace amounts in the early stages of most diseases that involve some sort of chronic inflammation in the body), and emit light when they encounter it"

Invent beowulf cluster of nanoparticles that glows in presence of disease

"Researchers have created a new nanoparticle that could someday act as a virtually all-purpose diagnostic tool to detect many inflammatory diseases..."
We can do anything now that science has invented magic

Heart disease and heart attacks certainly DO have a lot to do with inflammation. see the anti-inflammatory properties of lipitor, and see also the use of high-dose statins in the setting of acute MI. also, educate yourself on the pathophysiology of atherosclerosis and the role of macrophages.

The overproduction of hydrogen peroxide is implicated in the development of numerous diseases 1-4 and there is currently great interest in developing contrast agents that can image hydrogen peroxide in vivo.

and:

The overproduction of hydrogen peroxide is implicated in the development of numerous inflammatory diseases, such as atherosclerosis, chronic obstructive pulmonary disease and liver hepatitis 23-27.

I'm not an expert in these matters, but looking over the paper, it seems that there is considerable interest in this diagnostic technique for a variety of conditions. (The fact that it was published in a high-profile journal like Nature Materials is already a good indication.)

Most cancers, Alzheimer's and heart disease have nothing to do with inflammation, chronic or otherwise.

Actually, atheroma [wikipedia.org], the cause (in nearly all cases) of coronary artery disease, and the single commonest cause of death in the Western world, is well established to be an inflammatory process. The process of developing atheroma is influenced by a number of risk factors (e.g. diabetes, hypertension, hyperlipidaemia, smoking, obesity, family history); interestingly, rheumatoid arthritis is also a significant risk factor. It has even been hypothesised that various bacterial infections (which cause inflammation) may be a cause or risk factor for atherosclerosis, though studies looking at antibiotic treatment of these purported infections have not borne this out so far.

In fact, all of those diseases, including cancer, involve some degree of inflammation. And hydrogen peroxide is a key compound in inflammation, basically used as a general purpose "local disinfectant" by the body.

The peroxalate nanoparticles have several attractive properties for in vivo imaging, such as tunable
wavelength emission (460-630 nm), nanomolar sensitivity for hydrogen peroxide and excellent specificity for hydrogen peroxide over other reactive oxygen species.

In the paper, they demonstrate the use of this photo-marker in live mice, and are able to image the location of hydrogen peroxide anywhere in the mouse body. An obvious question regarding the technique is the toxicity of the nanoparticles. They do not discuss this in the paper (it will probably be the subject of an upcoming study), but the particles are ester polymers, with embedded dye (a pentacene derivative). So they are not using heavy-metal nanoparticles: these are peroxalate polymers. I'm not an expert in biocompatibility, but from the chemical structure, I wouldn't expect it to be highly toxic (it probably even degrades in the body).

Obviously a detailed toxicity study would be required before use in humans. However it's possible that it could be rapidly adapted to ex-situ diagnostics (e.g. on tissue explants) and then be adapted to live in-situ imaging if/when it is determined to be safe.

In the paper, they demonstrate the use of this photo-marker in live mice, and are able to image the location of hydrogen peroxide anywhere in the mouse body.

I see you've posted several times for this discussion, and that you've actually read the paper. As you pointed out earlier, pentacene is a fluorescent dye. However, that fact is misleading since its fluorescent properties are not utilized for this application. But what can you expect from a science blurb? They also spelled ester [wikipedia.org] as esther [wikipedia.org], so I ca

Sounds cool, except that I don't think they can perfect the no 'side-effects' part. Walk by the old leaky microwave in grandma's kitchen and suddenly all the nanobots begin to think that you are on their blacklist.

'Oops, my arm just fell off. Better check on what the heck those nanobots are up to today.'

That would utterly rock - no more ineffective drugs with side effects.

This of course raises the question of whether the drug companies that benefit from the current crop of drugs will stand for this. I imagine the smart ones are already working on nanoparticle based drug solutions. But truly effective drugs might not be so good for the bottom line! Nahhhh, no one would be that evil, riiiiiight?

Bacteria and viruses evolve, very very quickly in some cases. There is a reason the immune system can't stop all infections despite it's rather interesting complexity. The worst effect is of course false positives, losing all your neurons to a confused nanobot is not a fun thing.

Bacteria and viruses evolve, very very quickly in some cases. There is a reason the immune system can't stop all infections despite it's rather interesting complexity. The worst effect is of course false positives, losing all your neurons to a confused nanobot is not a fun thing.

I doubt that this would be specific enough (and of uncertain sensitivity) to be useful. How many false positives and false negatives would you get? It might end up being helpful in situations where you are looking to diagnose a suspected disease, but something this non-specific does not seem like it would be a good screening tool.

A few years back they were hawking full body (or if you were cheap partial body) CT scans as a screen. The brochures would show you the 38 year old mother of two whose renal cell carcinoma was detected and removed when it was 1cm in size, thus saving her life. They did not show you the guy who had a nodule detected on CT that looked suspicious, required a biopsy that caused a pneumothorax requiring a chest tube, that caused him to have a pneumonia with empyema, which caused respiratory failure, which caused him to be intubated for two weeks, needing a tracheostomy, etc.... to diagnose the totally benign lesion he had since he was born.

I wouldn't bet on this as the medical tricorder they are making it out to be.

I doubt that this would be specific enough (and of uncertain sensitivity) to be useful.

The paper [nature.com] goes into details of sensitivity and specificity. With regard to sensitivity they state:

The peroxalate nanoparticles were also capable of detecting hydrogen peroxide at concentrations as low as 250nM (Fig. 2b), and thus can detect hydrogen peroxide at physiologically relevant concentrations.

With regard to selectivity, they emphasize:

Another appealing feature of peroxalate nanoparticles for imaging hydrogen p

I'm not an expert in medical imaging, but a 50-fold selectivity and nano-molar detection limit seem medical usable. No doubt other techniques for detecting inflammation already exist, but this technique may be a useful addition to the diagnostic toolbox.

You are talking about something entirely different. When you talk about the sensitivity and specificity of a medical test that refers only to ratios of true/false positives/negatives. The sensitivity is 'of people who have the disease, how many will have a

You got the numbers wrong , it's Tc-99m and In-111.
And the problem with CT has never been about wrong diagnoses , or bad treatment , the problem is the radiation induced cancers. CT (and any other X-ray procedure) uses ionizing radiation and WILL statistically induce cancers in a number of patients. A problem that is also present with the mentioned Nuclear Medicine isotopes. Though on a much smaller scale since the energies are smaller and more specific. This nano-thing is very interesting because you can

It is not CT scans that I am saying are the problem. It is indiscriminate use of diagnostic tests as screening tests. The risk of doing the wrong test is far greater than people think. And the functional characteristics of tests (the positive and negative predictive values) change with use in different populations.

Take for example an HIV test that is 99.9% specific and 100% sensitive. That is, of 1000 positives, 999 are true positives. Sounds like a good test, right?

I don't disagree with you about the concept of screening healthy people, in most cases, it's a bad idea.
But don't tell me somebody have been using CT for screening - was that in the US ?
I live in Denmark where there was a minor debate a couple of years ago regarding screening mid-aged women for brest cancer. Your exact argument was the primary reason a lot of doctors opposed the idea. But even if they use X-ray for screening it's nowhere near as risky as doing full body CT. And the primary proponent of th

"I don't disagree with you about the concept of screening healthy people, in most cases, it's a bad idea."

Its not that screening is a bad idea. Its that BAD screening is a bad idea. Medical screening (like for hypertension, diabetes, obesity, depression, alcoholism, certain types of cancer like cervical, breast, colon, domestic violence, etc) is a GREAT idea and has saved the lives of millions. However, for a test to be a valid and good screening test, it much meet some very specific criteria. The ultimate